The invention relates to a seam-weaving machine for making a fabric endless, which weaves a woven seam out of fringes formed at the opposed fabric ends and from weft threads removed from the fabric. Fringes, aligning with each other in each case, of the fabric ends are guided upwards and/or downwards out of the woven seam at splice points which are distributed over the width of the woven seam. The invention further relates to a fringe catcher for such a seam-weaving machine, which fringe catcher has an arm, movable by a drive device, with a hook at the front end, which hook grasps the fringe ends protruding from the woven seam and lays them aside in such a way that they do not interfere as the weaving process continues.
Industrial plastics fabrics for uses in which a very regular surface structure of the fabric is required, in particular flat-woven plastics paper forming fabrics, are made endless by a woven seam. To produce a woven seam, warp threads are exposed to a length of about 20 cm at the fabric ends which are to be joined to each other, the weft threads being removed from this zone. The woven seam, in which the original weave binding is exactly reproduced, is then formed from these warp thread fringes and the weft threads removed from the fabric ends. For this purpose, an auxiliary weaving shed or seam-weaving shed is spread out from the removed weft threads, in which shed the removed weft threads function as auxiliary warp threads. The warp thread fringes are inserted into this auxiliary weaving shed as auxiliary weft threads alternately from the two fabric ends. The warp thread fringes are not inserted over the full width of the seam-weaving shed, but are guided out of the seam-weaving shed at a so-called splice point. The warp thread fringe, aligning with it, of the other fabric end is likewise inserted into the seam-weaving shed only up to this splice point. The inserted lengths of the warp thread fringes, aligning with each other, of the two fabric ends thus supplement each other to the full width of the woven seam. The splice points are distributed over the woven seam in a pattern, so that the tensile strength of the woven seam is as high as possible.
DE-U-81 22 449 discloses a piercer finger which, in the case of a seam-weaving machine which has a heald frame shedding device, reaches or pierces through the auxiliary warp threads of the upper shed and draws out, upwardly from the shed, the auxiliary weft thread initially inserted over the full width of the woven seam. At its front end, the piercer finger is fitted with a clamping device for this purpose. The piercer finger is swivellable and displaceable parallel to the auxiliary warp threads and also movable over the width of the woven seam.
EP-A-43 441 discloses a seam-weaving machine with a Jacquard shedding device. A piercer finger is not necessary in this case, as the tying-in of the auxiliary weft threads into only a part of the width of the woven seam is achieved by virtue of the fact that the shed is stretched over only a corresponding part. In this case, it depends on the insertion position of the draw-through gripper whether the ends of the warp thread fringes protrude upwardly or downwardly from the woven seam. In general, the warp thread fringes protrude on the running side of the paper-forming fabric, so that they cause no marking in the paper.
U.S. Pat. No. 4,581,794, issued on Apr. 15, 1986 to Malcolm Oldroyd, et al. likewise discloses a seam-weaving machine operating with a Jacquard shedding device. This seam-weaving machine has two extractors attached laterally directly outside the woven seam, which are intended to take over the warp thread fringe drawn through the seam-weaving shed by a draw-through gripper and draw it out upwardly. Problems arise, however, as the draw-through gripper moves below the plane of the fabric, while the extractor is arranged above the plane of the fabric and outside the woven seam width, with the result that the extractor would have to grasp through the fabric end.
Paper-forming fabrics often consist of two fabric layers which are bound to each other by special binding threads. When such multi-layered fabrics are being made endless, it is not desirable to guide all the warp thread fringes out to one side, generally the running side, since the ends of the warp thread fringes of the paper-side fabric layer would then, deviating from the binding pattern, have to be guided through the running-side fabric layer. This will result in a fault in the binding pattern and, because of the higher thread volume, a reduction in water permeability, which leads in turn to a marking in the paper.